If the file does not exist and it is opened for output, it should be
created as a new file. If mode is WriteMode and the file
already exists, then it should be truncated to zero length.
Some operating systems delete empty files, so there is no guarantee
that the file will exist following an openFile with modeWriteMode unless it is subsequently written to successfully.
The handle is positioned at the end of the file if mode is
AppendMode, and otherwise at the beginning (in which case its
internal position is 0).
The initial buffer mode is implementation-dependent.

This operation may fail with:

isAlreadyInUseError if the file is already open and cannot be reopened;

isDoesNotExistError if the file does not exist; or

isPermissionError if the user does not have permission to open the file.

Note: if you will be working with files containing binary data, you'll want to
be using openBinaryFile.

Like openFile, but open the file in binary mode.
On Windows, reading a file in text mode (which is the default)
will translate CRLF to LF, and writing will translate LF to CRLF.
This is usually what you want with text files. With binary files
this is undesirable; also, as usual under Microsoft operating systems,
text mode treats control-Z as EOF. Binary mode turns off all special
treatment of end-of-line and end-of-file characters.
(See also hSetBinaryMode.)

Like openFile, but opens the file in ordinary blocking mode.
This can be useful for opening a FIFO for reading: if we open in
non-blocking mode then the open will fail if there are no writers,
whereas a blocking open will block until a writer appears.